A safety device for an injection syringe is already known that has a protective sheath that is triggered at the end of injection so as to cover the injection needle and thus avoid any contamination. An example of such a device is described in document FR 2 922 112.
Generally, such a device has flanges, or a collar, serving as a bearing surface for the fingers of the user performing the injection.
A difficulty lies in the fact that those grip flanges can be too small for people suffering from inflammatory joint pain or who have difficulty in manipulating or in applying sufficient force on items of small size, for example people suffering from rheumatoid arthritis.